1. Field of the Invention
This invention relates to a method and apparatus for transplanting seedlings, grown in molded pulp planting blocks conjoined in tray-like groups, into a plurality of furrows where they are individually and selectively spaced. It particularly relates to a method and apparatus for high-speed transplanting of such seedlings with a minimum of hand labor and further relates to a method and apparatus for minimizing gaps caused by non-germinated seeds.
2. Review of the Prior Art
A plant setting machine which is drawn by a tractor is described in U.S. Pat. No. 2,959,141. Operators stand or sit at each side of the machine, select plants from supply hoppers, and place them on a plant tray structure in the operating path of planting arms.
A pineapple planting machine which includes a frame that is adapted to be mounted on a conventional tractor and a planter which is arranged rearwardly of the tractor for automatically inserting and positioning a plurality of pineapple shoots or plants in the ground at the proper locations is described in U.S. Pat. No. 3,002,473. Workmen standing on a platform take pineapple shoots from a feed basket or hopper and place them butt end down into the plant trough between planting blade assemblies. The plants are crowded through and to the end of the trough by a metal plate and are injected by rollers into an opening prepared by a vibrated roller.
A planting apparatus comprising a storage conveyor which delivers plants in plastic bags to one end, an unbagging conveyor which advances each plant over a pair of stripping belts for stripping the plastic bags from the generally cylindrical plug of earth enclosing the plants, and a pusher-like plant dispensing member which dispenses each plant from a holding station into a furrow is described in U.S. Pat. No. 3,524,419.
A plant transplanting apparatus which is designed for transplanting seedlings which have been grown in a tray made of a thin plastic sheet or metal foil is described in U.S. Pat. No. 3,712,252. This automatic transplanter is adapted to support and index a plurality, such as four, of seedling growing-and-handling devices and includes four indexing openings and drop pipes or tubes which are connected to a source of reduced pressure whereby suction assists in discharging the seedlings in their respective growth zones when placed over an index opening and bearing plate.
A planting machine that is capable of transplanting potted plants and is incorporated in a trailer vehicle having a plurality of receptacle sub-assemblies which are disposed at an even angular spacing around the axis of a shaft is described in U.S. Pat. No. 3,872,805. Potted plants which are arrayed on trays on this planting machine are manually removed by a seated operator and are successively placed in receptacle sub-assemblies by a power-transfer system between the wheels and the shaft so that the velocity of the lowermost receptacle sub-assembly is substantially zero with respect to the ground as the contents of the receptacle are placed in an opening therein.
A transplanting machine, combining a hotbed feed frame and a motor supporting frame upon forward traction wheels, is described in British Pat. No. 324,865. Adjacent to the hotbed frame is a trough which is provided with the upper portion of an endless belt movably mounted therewithin, whereby hotbeds, caked into angular molds, are longitudinally arranged and placed close to one another on the frame while being supported in parallel upon two or more laterally travelling belts which move the group of hotbeds towards the trough while one mold is being moistened with water. The cake hotbed is then separated from its mold by contact with a sharp edge and a wedge and laid into a suitable furrow made by a plow.
A combine machine which provides means for establishing a seedling plant nursery upon its frame in order to produce a supply of seedlings and permit them to grow unhindered for transferring to their permanent position in the cultivated soil is described in British Pat. No. 1,214,058, the seedlings moving gradually from the position where the seed is sown to the position from which they can be readily planted. Trays in the form of long troughs are supported at a slope in compost which is divided into individual portions containing a single grown seedling, the trays being linked together to be movable as a whole to a limited extent transversely of the machine by a belt in each tray. Successive belt movements cause the compost to be cut into sections by the blades of a cutting device.
A planting machine for planting cartridges containing grown plant seedlings in a furrow formed by a furrower and for covering the cartridges with a soil closing implement is described in Canadian Pat. No. 634,508. The seedling cartridges are placed on trays or magazines and are shifted to planting chutes which tilt down until they abut against the bottom of a furrow, whereby the seedling cartridges slip down and are erected to a substantially vertical position while soil is closed around them.
Productivity has generally been limited by two factors when attempts have been made to mechanize the transplanting operation. Most machines function by opening the soil to form a furrow, grasping the individual plants, releasing them in position in a furrow, and firming the soil around the plants. The grasping mechanism is usually fed by hand, using one or two operators per row planted, so that the speed is limited by operator dexterity as the first factor. The second factor is the necessity to handle the seedlings by their stems, thus often requiring a longer growth period in the greenhouse than is optimum for the species being transplanted. A compromise is consequently made between stem durability and transplant shock, and die-offs caused by damaged stems tend to limit productivity. Furthermore, mechanical transplanting at the present time tends to involve a small army of laborers who move at a very slow pace in the field.
There is consequently a need for greatly improving the speed of mechanical transplanting, its efficiency as measured by percentage survivals, its efficiency as measured by machine time per traverse of the transplanting machine. Furthermore, there is need for utilizing the latest developments in the art of growing seedlings so that the seedlings can be manipulated, spaced apart, placed in a furrow, and covered with firmed soil without touching the stems or putting any pressure upon the plants themselves. There is still further a need to incorporate modern methods for growing seedlings in molded grow blocks and then for culling, rejecting, or replacing each grow block that lacks a seedling, whereby planting efficiency can be increased by producing a more perfect stand.